1. Field of the Invention
The present invention relates to light guide plates (LGPs) of liquid crystal displays (LCDs), and backlight systems using such LGPs.
2. Description of the Prior Art
A typical LCD device comprises an LCD panel, and a backlight system mounted under the LCD panel for supplying light beams thereto. The backlight system mainly comprises a light source and an LGP. The LGP is normally a transparent polymer plate, and is used for guiding light beams emitted by the light source to uniformly illuminate the LCD panel.
FIG. 3 represents a backlight system 1 as disclosed in U.S. Pat. No. 6,443,583. The backlight system 1 includes a light source 110, a light source cover 120, and an LGP 200. The LGP 200 comprises a light incident surface 201, a light emitting surface 203 adjoining the light incident surface 201, and a bottom surface 202 opposite to the light emitting surface 203. The backlight system 1 further comprises a reflective sheet 210 underlying the bottom surface 202, a diffusion sheet 220 adjacent the light emitting surface 203, a prism sheet 230 disposed on the diffusion sheet 220, and a protecting film 240 disposed on the prism sheet 230. The prism sheet 230 serves to redirect diffused light emitting from the diffusion sheet 220 so that it is more concentrated.
In operation, the light source 110 emits light beams and the light beams are transmitted into the LGP 200. The reflective sheet 210 reflects the light beams and directs the light beams to exit from the light emitting surface 203. The light beams then sequentially pass through the diffusion sheet 220, the prism sheet 230 and the protecting film 240 to illuminate a liquid crystal panel (not shown).
The LGP 200 is conventionally made of a polymethyl methacrylate (PMMA) resin. In general, the transmittance of light of PMMA is in the range from 91%˜92%. This relatively low transmittance of light reduces the light utilization efficiency of the backlight system 1.
It is desired to provide a backlight system and an LGP used therein which overcome the above-mentioned problem.